AUTHORS: Leah K. Berkman, Missouri Department of Conservation; Christopher J. Rice, Missouri Department of Conservation; Brandon L. Brooke, Missouri Department of Conservation; Jacob T. Westhoff, U.S. Geological Survey, Missouri Cooperative Fish and Wildlife Research Unit
ABSTRACT: The ecological conditions that create biodiversity hotspots (i.e., cradles) are thought to operate similarly at intra- and interspecific levels. The Central Highlands of the eastern US is thought to be such a region for aquatic taxa where many species exist and, within the species, populations are highly distinct. Darters (Percidae: Etheostomatinae) in particular have undergone multiple rounds of allopatric speciation largely owing to headwater specialization and isolation by large rivers. The Niangua Darter (Etheostoma nianguae) is a central Missouri endemic, isolated from its most closely related species group, the Arrow Darters (E. spilotum and E. sagitta), by the Mississippi River. To inform federal recovery plans we investigated patterns of genetic diversity across the extant range of the Niangua Darter which consists of five distinct tributary systems of the Osage River. Samples from each tributary system were analyzed (n = 75) along with representatives from 3 outgroup species (n = 8) using reduced representation whole genome sequencing (RADSeq). Variant filtering resulted in 66 samples genotyped at 1,354 single nucleotide polymorphisms (SNPs). The five tributary systems were highly distinct from one another (FST= 0.116-0.375) conforming to the aquatic biodiversity patterns often observed in the unglaciated portion of Missouri. The Niangua Darter represents one of the smallest scales over which the pattern of biodiversity in darters has been replicated in the Central Highlands. The patterns in genetic diversity among populations that we describe can inform managers when considering actions that may affect persistence across the species range or involve translocation or stocking of individuals.
